Set numberOfItemsInSection at Runtime - UICollectionView - ios

Question

I would like to set the numberOfItemsInSection of my collectionView at runtime. I will be changing the value programmatically at runtime quite often and would like to know how.
I have an array of images to display in my UICollectionView (1 image per UICollectionViewCell), and the user can change the category of the images to display, which will also change the number of images to display. When the view loads, the numberOfItemsInSection is set to the count of the allClothingStickers array. But number this is too high. The array that does get displayed is the clothingStickersToDisplay array which is a subset of the allClothingStickers array.
There is this error after some scrolling:
fatal error: Array index out of range
This is because the number of items has become smaller, but the UICollectionView numberOfItemsInSectionproperty has not changed to be a smaller number.
I have this function that sets the number of cells in the UICollectionView before runtime.
func collectionView(collectionView: UICollectionView,
numberOfItemsInSection section: Int) -> Int {
return self.numberOfItems
}
This function to set the stickersToDisplay array (and I want to update the numberOfItemsInSection property here):
func setStickersToDisplay(category: String) {
clothingStickersToDisplay.removeAll()
for item in self.allClothingStickers {
let itemCategory = item.object["category"] as! String
if itemCategory == category {
clothingStickersToDisplay.append(item)
}
}
self.numberOfItems = clothingStickersToDisplay.count
}
This is the function that returns the cell to display:
func collectionView(collectionView: UICollectionView,
cellForItemAtIndexPath indexPath: NSIndexPath)
-> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(
identifier,forIndexPath:indexPath) as! CustomCell
let sticker = clothingStickersToDisplay[indexPath.row]
let name = sticker.object["category"] as! String
var imageView: MMImageView =
createIconImageView(sticker.image, name: name)
cell.setImageV(imageView)
return cell
}
EDIT: Oh yeah, and I need to reload the UICollectionView with the new clothingStickersToDisplay at the same place that I update it's numberOfItemsInSection

Answer 1

I think what you should do is to clothingStickersToDisplay a global array declaration.
Instead of using that self.numberOfItems = clothingStickersToDisplay.count
Change this function to
func setStickersToDisplay(category: String) {
clothingStickersToDisplay.removeAll()
for item in self.allClothingStickers {
let itemCategory = item.object["category"] as! String
if itemCategory == category {
clothingStickersToDisplay.append(item) //<---- this is good you have the data into the data Structure
// ----> just reload the collectionView
}
}
}
In the numberOfItemsInSection()
return self.clothingStickersToDisplay.count